Quantum phase transitions in the disordered chalcogenide topological insulators (Bi<sub>1-x</sub>Sb<sub>x</sub>)<sub>2</sub>Y<sub>3 </sub>and X<sub>2</sub>(Te<sub>y</sub>Se<sub>1-y</sub>)<sub>3</sub>, (X = Bi/Sb, Y = Te/Se)
ORAL
Abstract
Topological systems with various Bi/Sb and Te/Se concentrations have been studied with a view towards tuning topological phase transitions, and we try to clarify this by varying the lattice parameters in this family of materials and driving electronic topological-to-trivial phase transitions. We first investigate disorder on each site and perform first-principles calculations on (Bi1-xSbx)2Y3 and X2(TeySe1-y)3 (X=Bi/Sb, Y=Te/Se) in which we systematically vary the c/a ratio of lattice constants to study the topological phase transition, before studying alloying on all sites. To model substitutional disorder, we have constructed supercells, alloying on one sublattice, where the atomic pair correlations are zero up to the third nearest neighbor shell, and we vary the impurity concentration across the phase diagram with the goal of identifying the influence of each atomic species on the transition. We determine the bulk electronic structure and pay special attention to the band inversion near the topological transition.
*K.S. and I.V. were funded by NSF Grant No. DMR-1410741, K.S. and W.A.S. were funded by U.S. DoE EPSCoR Grant No. DE-SC0012432 and Louisiana Board of Regents, and high performance computing resources were provided by Louisiana State University (http://www.hpc.lsu.edu). Work at Ames Laboratory (P.S. and D.D.J., and partially W.A.S.) was funded by the U.S. DOE Office of Science, Basic Energy Sciences, Materials Science & Engineering Division; research was performed at Iowa State University and Ames Laboratory, which is operated by ISU for the U.S. DOE under contract DE-AC02-07CH11358.
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Presenters
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Karunya Shailesh Shirali
- Louisiana State University